Process of making allo citral.



STATES PATENT FFICE.

WILHELM KRAUTH, OF GRIESHEIM, GERMANY.

PROCESS OF MAKING ALLO CITRAL.

SPECIFICATION forming part of Letters Patent No. 654,649, dated July 31, 1900. Application fileq November 23,1899. $erial No. 788,091. (No specimens.)

To 'aZZ whom itmay concern.-

Be it known that I, WILHELM KRAUTH, a subject of the King of Prussia, German Empire, residing at Griesheim-on-the-Main, Germany, have invented certain new and useful Improvements in Processes for the Preparation of 2.6 Dimethyl, 2.5 Octdienal 8, (for which I have applied for a patent in Germany, dated February 3, 1899,) of which the following is a specification.

Although, according to theory, numerous isomeric alipathic aldehydes of the terpene series having the formula C H O should be possible, one alone-'namely, citral, (gernial,)-'-is known. The constitution of citral has been settled by thework of Tiemann, Semmler, Barbier, Verley, and others by analysis of the citral molecule, which may be split up first into acetaldehyde and methylhexylenketone and then, by further decomposition of the latter, into acetone and levulinic acid, so that the formula 0H, on,

may be deduced. Furthermore, the work of Tiemann and of Dobner shows that Stiehls assertion that three aldehydes may be isolated from lemon-grass oil, which differ from each other by the position of their double bonds, arises from faulty observation. I have succeeded now in preparing synthetically an aliphatio aldehyde of the formula 0 11 0 which differs from citral and Whose constitution follows directly from its mode of formation. I have found, in fact, that when methylhexylenketone of the formula:

, 01-1 0; cum-1 00.011,

' into dichlorooctene I on, on,

from which, by elimination of hydrogen, chlorid chloro octane 011 .0. 0H. 0H,. CH: 001 I 0H,. 0; CH. 0H,. CHE 011 00011 allo geranie acid, (new acid.)

0H,. 0; 011011 0110; OH. 00011 0H 0H,

geranic acid. When a dry mixture of equivalent quantities of octinyl acetate of barium and barium formate is distilled in a vacuum, a good yield is obtained of allo citral, the aldehyde corresponding with allo geranic acid and isomeric with citral. Its formula is This aldehyde may be obtained also, although in small yield, by the dry distillation of a mixture of the barium salt of octinyl malonic acid with barium formate.

The following examples illustrate the op erations.

Example 1: One hundred and twenty-five parts of methylhexylenketone are allowed to drop slowly upon two hundred and ten parts of phosphorus penta chlorid. When all has been added, the mixtureis heated on the Water-bath until the development of hydrogen chlorid has ceased. The phosphorus oxychlorid is then decomposed by addition of water, and the chloro octin is distilled over with steam. It is thus obtained sufficiently pure for the subsequent operations.

Example 2: One hundred and forty-five parts of chloro octin are heated in alcoholic solution with one hundred and eighty-two parts of ethyl sodiomalonate in reflux apparatus until, after two or three hours, the reaction of theliquidis neutral. After the al cohol has been distilled offi water is added and the octinyl malonic acid diethylester is separated from the aqueous solution of sodium chlorid. By saponifying by known methods 'there is obtained from this ester the freeectinyl malonic acid. 4

Example 3: The last-named acid is slowly distilled in a vacuuin'in anioil ba'tlij Carbon dioxid is evolved andthe octinyl-acetic acid, named allo geranic "acid, is obtained as the distillate.

Example 4: An intimate mixture of fortyseven partsof dry barium salt and 22.5 parts of dry barium formate is distilled in a vacu- 11m. A. good yield of allo-citral is obtained.

Example 5: For thepreparation of this aldehyde from octinyl malonic acid thirty-five parts of the dry barium salt of .this acid are mixed with twenty-five partsof drybariurn 5 '=formate, and the mixture is distillated as described in Example 4:. r

The new aldehyde (allo-citral) is applicable for the manufacture of perfumes.

What I claim, and desire to secure by Let- 3o ters Patent of the-United States,.is-

A process for the preparation of allo citr'al by first converting methylhexylenketone into chloro octin then converting the latter by .malonic acid diethylester, then saponifying this ester to-obtain'the free acid, and finally distilling a dry mixtureof the barium salt of this octinyl malonic acid obtained by eliminating carbon dioxidfrom this-aforesaid'acid', 40

with; barium formate, substantially as described. i

.. In testimony whereof I have hereuntoset my hand in the presence of two witnesses.

. WILHELM KRAUTH.

Witnesses: V

RICHARD GUENTHER,

CARL GRUND.

-m-eans of ethyl sodiomalonate into octinyl 35 

